Research | Feb 2022

VALUE OF MICROCLIMATES IN THE KALAHARI

Grace Warner

Hot and dry areas in southern Africa, like the Kalahari, are predicted to get even hotter and drier with climate change. Such changes will continue to pose a challenge for an ecosystem in which organisms are already living on the extreme edge of survival. Without enough water, plants are likely to die, and without plants at the base of the food chain, the whole system will struggle to survive. Yet, if both plants and animals can find small areas in their environment that gather moisture and provide shelter from harsh radiation, there is hope that they may be able to cope, even when the large-scale climate is not in their favour.

A Cape cobra on its way to using a tree cavity to escape the afternoon heat.

Grace Warner, a Master’s student from the University of the Witwatersrand, is spending a year at Tswalu Kalahari Reserve, working on a project that aims to figure out exactly what small areas are available for animals to shelter in, what topography they are associated with and how much shelter they actually provide. Her project falls under the umbrella of the Kalahari Endangered Ecosystem Project, a multidisciplinary study investigating how organisms are responding to climate change.

These ‘small areas’, which are known as microclimates, experience a different climate to the unsheltered surrounding areas. In the Kalahari environment, microclimates are created by structures like burrows, bird nests, rock crevices, cavities in trees or even the shade provided by plants.

A CHEETAH MOTHER ESCORTS HER CUBS BACK TO THEIR DEN ON THE MOUNTAINSIDE. ROCK CREVICES PROVIDE PRIME THERMAL REAL ESTATE FOR DENS, SHELTERING YOUNG ANIMALS FROM BOTH EXTREME TEMPERATURES AND PREDATORS.

To figure out the densities and distribution of microclimates, Grace travels across distinct environmental gradients in the reserve, and uses transects to gain insight into the availability of specific microclimate types. She also has a set of about 80 thermal data loggers hidden around the reserve in various microclimates. These loggers take temperature recordings every half hour and allow her to compare microclimatic temperatures to exposed ‘large-scale’ temperatures over time.

GRACE USES THE KEEP RESEARCH TEAM’S ALL-TERRAIN SUZUKI JIMNY TO JOURNEY TO THE FAR REACHES OF THE RESERVE, BUT ALSO WALKS LONG DISTANCES IN THE DUNES AND MOUNTAINS AND ACROSS THE PLAINS; IMAGE BY DYLAN RICE.

Some microclimates in the Kalahari have already been studied in terms of their thermal properties, like the impressive sociable weaver nests and aardvark burrows. Sociable weaver nests have been shown to be up to 20 percent cooler in the nesting chambers than outside the nests, providing ideal nesting and resting temperatures for many Kalahari bird and reptile species. Similarly, aardvark burrows have been shown to provide a more thermally stable and humid microclimate for up to nearly 30 different vertebrate species that use the burrows after the aardvarks have abandoned them.

A CAPE GROUND SQUIRREL'S BURROW PROVIDES ANOTHER REMARKABLY BUFFERED MICROCLIMATE FOR MANY RODENTS AND REPTILES, ALLOWING THEM TO SURVIVE THE ICY NIGHTS OF WINTER AND THE SCORCHING KALAHARI SUMMER DAYS.

With her current project, Grace is attempting to gain more insights like these into a wider variety of microclimates. By understanding which microclimates are most capable of buffering temperatures over time, we can predict which microclimates will be most important for species to use in sheltering from climate change. Even better, if we can recognize in which areas those preferred microclimates are located, we can earmark those areas for increased conservation protection, increasing the chances that Kalahari species will have a place to hide when the climate changes beyond what species have been able to tolerate in the past.

EVEN SHADE FROM VEGETATION CAN PROTECT ANIMALS FROM THE SUN. A JUVENILE SPOTTED EAGLE-OWL MAKES USE OF DAPPLED SHADE IN A TREE.

Many thanks are owed to all the supporters of Grace’s project, namely Oppenheimer Generations Research and Conservation, The Rufford Foundation, Suzuki Auto South Africa, and donations from Escape Safari Co. and the Warren Cary Art Exhibition that were gratefully received through support from the Tswalu Foundation.

 

All images by Grace Warner, except where individually credited.

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